1. Field of the Invention
The present invention pertains to magnetic tape which is used for transducing information, and particularly to identification of magnetic tape cartridges.
2. Related Art and Other Considerations
For decades information has been stored on magnetic tape medium using tape drives. Initially the magnetic tapes were wound about large reels in similar manner as film for early film projectors. In more recent years the magnetic tape has typically been housed in a cartridge or cassette, extending internally in the cartridge from a supply reel to a take-up reel. In some systems, the magnetic tape has longitudinal tracks recorded thereon (e.g., tracks that extend along the major length dimension of the tape). In other systems, the path of the magnetic tape is such that the tape is at least partially wrapped around a drum in a manner to transduce helical stripes or tracks on the magnetic tape. Some of the cartridges have a lid or the like which is displaced upon insertion of the cartridge into the tape drive, thereby exposing the magnetic tape to operative elements of the tape drive (e.g., tape guides, tape transport mechanisms, and transducing elements). Other cartridges are fabricated with a window or the like into which operative elements of the tape drive extend when the cartridge is loaded into the tape drive.
Some magnetic tape/cartridge manufacturers have developed techniques whereby, upon insertion into a tape drive, the tape/cartridge is identified as being of a certain type. For example, Minnesota Mining and Manufacturing Company (3M) has developed a pattern of holes formed in a tape which are optically detected as an indication that the tape is a quarter inch cartridge (QIC) tape. Similarly, Sony Corporation has a DDS pattern for 4 millimeter digital audio tape (DAT) identification, and a RS pattern for 8 millimeter MP identification (MP refers to metal particle coating type tape) .
Debris and dust can collect internally in tape drives and eventually on magnetic tape itself. The presence of such debris or dust on the tranducing element(s), either by contact with the tape or otherwise, can lead to degredation of signal quality and thus decreased performance of the transducing element(s) and the tape drive overall. To counteract the problem of debris or dust aggregating on the tranducing element(s), typically periodically a cleaning cartridge is loaded into the tape drive. The cleaning cartridge resembles a tape cartridge in most aspects, but the media extending from the supply reel to the take-up reel is a cleaning material rather than magnetic tape. The cleaning material comprising the media is transported past the tranducing element(s) in a manner to wipe gently the tranducing element(s), thereby removing dust and debris. U.S. Pat. No. 5,369,285 to Georgis provides optical detection of cleaning medium in an information storage drive.
It has been know to combine both magnetic tape and some the of cleaning material on the same media. For example, U.S. Pat. No. 4,422,119 to Kawakami et al. forms at least part of a leader for magnetic tape with an abrasive cleaning material. U.S. Pat. No. 5,638,236 to Scott discloses tape having a first (preferably magnetic) portion with a cleaning leader directly spliced thereto. U.S. Pat. No. 4,893,209 to Siddiq provides multifunction cleaning tape that also has a segment for providing diagnositic/instructional information to a user.
What is needed, and an object of the present invention, is a magnetic tape that provides both cleaning and self-identifying capabilities.
Media for use in a magnetic tape drive has a magnetic recording/reproducing segment for magnetically transducing information; a cleaning segment; and, an identification window segment. The identification window segment is situated intermediate the magnetic recording/reproducing segment and the cleaning segment, and has an electromagnetic transmissiveness which differs from the magnetic recording/reproducing segment and the cleaning segment. Preferably, the identification window segment is transparent to a predetermined wavelength range (e.g., infrared) while the magnetic recording/reproducing segment and the cleaning segment are opaque to the same predetermined wavelength range. The identification window segment has a dimension (e.g., length) chosen to provide a predetermined media or cartridge signature when the media is transported at a selected linear velocity.
Upon insertion into a magnetic tape drive, the magnetic tape is transported past a detector assembly which directs a beam of electromagnetic radiation through the tape. Whereas the cleaning segment and magnetic recording/reproduction segment do not transmit the beam therethrough, the identification window segment does. Transport of the identification window segment past the detector assembly thus results in generation of a signal having a pulse width related to the length of identification window segment. The signal is received at a processor, which uses the signal to determine the type of the tape/cartridge and optionally to operate the tape drive in accordance with the thusly discerned type.